This invention relates to a method of assessing the odor intensity of gas which can be effectively used in lieu of an organoleptic odor intensity evaluation.
It is known that an organoleptic evaluation is appropriate for measuring the odor intensity of gas. However, an organoleptic evaluation of the odor intensity of gas cannot be consistently performed in an industrial setting. Accordingly, other methods for evaluating the odor intensity of gas have been developed.
For example, a method for measuring the odor intensity of exhaust gas from a diesel engine was proposed in a lecture reported in the Transactions of the Society of Automotive Engineers of Japan, which was authored by Kato et al. and published in October, 1977. In this method, formaldehyde is quantitatively analyzed as an odor-producing substance. In their results, the actual concentration of formaldehyde best correlates with the organoleptically evaluated odor intensity. It was reported that the correlation between all the organoleptically evaluated odor intensities of exhaust gas from four types of diesel engines and the concentrations of formaldehyde in the exhaust gas is 0.54. Therefore, Kato et al. proposed quantitatively measuring odor intensity of diesel exhaust by measuring the concentration of formaldehyde in the exhaust gas.
This strong correlation between the concentration of formaldehyde and the organoleptically evaluated odor intensity can be obtained when the data of all the diesel engines tested is analyzed. However, when the odor intensity of the exhaust gas from a specific engine is measured, the concentration of formaldehyde does not always correlate with the organoleptically evaluated odor intensity. Since various compounds in the exhaust gas produce odor, the odor intensity of the gas cannot be precisely measured by measuring the concentration of formaldehyde alone.
For example, the concentration of formaldehyde in the exhaust gas from a diesel engine running for a long time, a direct-injection diesel engine running for a short time, or a diesel engine with an auxiliary combustion chamber running for a short time may not correlate with the organoleptically evaluated odor intensity of the exhaust gas.
By this prior-art method, the odor intensity of the exhaust gas from a diesel engine or that of the air exhausted from an air conditioner cannot be quantitatively measured, since the formaldehyde does not correlate with the organoleptically evaluated odor intensity.